286 TRANSACTIONS LIVEEPOOL BIOLOGICAL SOCIETY. 



DISEASES AND PARASITES OF FISHES. 

 By JAS. JOHNSTONE, D.Sc. 



CONTENTS. page 



Septic Ulcers in Cod ; Malnutrition of North Sea Fishes in 1921 ... 286 

 Various Fish Tumours — 



(1) A Benign Tumour in a Plaice 291 



(2) Sarcoma in a Haddock ... ... ... ... ... ... 291 



Cestode Degeneration Cysts in a Trout ... ... ... ... ... 294 



The " Oyster Parasite," Gasterosto mum gracilescens 297 



A Myxosporidian in a Hake ... ... ... ... ... ... 299 



Septic Ulcers in Cod and other Marine Fish : 

 Malnutrition of North Sea Fishes in 1921. 



Between September, 1921, and March, 1922, a number of 

 specimens of diseased cod and other marine fishes were received : 

 all of them were taken in the S.W. part of the North Sea. 

 The sendings were: 27th Sept., 1921, codling; 24th Oct., 

 cod; 27th Oct., cod ; 4th Nov., cod; 7th Nov., cod, 2 plaice ; 

 17th Nov., 2 plaice, codling, haddock; 24th Nov., cod; 

 28th Nov., plaice, sole ; 20th Jan., 1922, cod ; 14th Jan., cod. 

 All these fish were taken inshore, or at a greatest distance from 

 the land of about 60 miles. 



The same general affection was displayed by all these 

 fishes. There were large, shallow ulcers on the surface of the 

 body, destroying the skin and eating down into the flesh to a 

 depth of about one quarter of an inch. In most cases there 

 were several ulcers, or sores, and usually on both sides of the 

 fish. In several cases there was healing — this I refer to later 

 on. Sometimes there were red, highly-inflamed patches on 

 the skin, without erosion of the latter. In other cases there 

 were places where there was no ulceration, but where the scales 

 were apparently raised up and swollen, and with swellings in 

 the skin below the scales. 



Usually the fish were in " poor " condition, or were 



